Constrictable tube valve with anti-cracking tube arrangement and tube therefor

ABSTRACT

An internal circumferential rib is provided on the inner surface of a tube of inelastic crack sensitive resin. The side edges of the tube coinciding with the rib are clamped in folded condition to establish fluid seals thereat. Compressor members effect selective constriction of the remainder of the tube between the clamped edges to provide valving action in a constrictable tube valve. Provision of the rib prevents the development of throughthe-wall cracks.

United States Patent 1 1 Rink 1 1 Nov. 6, 1973 [54] CONSTRICTABLE TUBEVALVE WITH 2,342,192 2/1944 Gri sby 251/8 ANTI-CRACKING TUBE ARRANGEMENTg k W1C AND TUBE THEREFOR 3,204,919 9/1965 Tripoli et al. 251/8 [75]Inventor: Helm Arthur Rink, North Haledon,

Primary Examiner-George E. Lowrance [73] Assignee: ResistoilexCorporation, Roseland, Ass'stam Examinerhsteverf Pollard NiAtt0rneyElmer R. Helfench et al.

[22] Filed: Dec. 15, 1971 [57] ABSTRACT [21] Appl' 208279 An internalcircumferential rib is provided on the inner surface of a tube ofinelastic crack sensitive resin. The 52 us. (:1. 138/121, 251/8 Sideedges of the tube coinciding with the rib are [51] Int. Cl. F16] 11/00clamped folded Condition to establish fluid Seals [58] Field of Search138/121, 46, 108, thereat- Compressor members effect selective constric-13 11 119; 251/7 3 4 tion of the remainder of the tube between theclamped edges to provide valving action in a constrictable tube [56] Rferen Cit d valve. Provision of the rib prevents the development ofUNITED STATES PATENTS through-the-wall cracks.

2,212,733 8/1940 Grigsby 251/8 7 Claims, 6 Drawing Figures 'IIIH a i I5?-l8 111 1 19.2%

% I 26 :1: \7 l 1 Z' 22 m//////////4 //////////2 coN'STRICTABLE TUBEVALVE WITH ANTI-CRACKING TUBE ARRANGEMENT AND TUBE THEREFOR DISCLOSUREThe present invention relates to the constrictable tube utilized in avalve of the type which mechanically flattens such tube to form abarrier to the flow of material therethrough. More specifically, theinvention is directed to a solution to the problem of crack formation inthe wall of the constrictable tube during use when such tube isfabricated from a substantially inelastic and crack sensitive material.

In the copending application of Irving D. Press, Ser. No. 126,436, filedMar. 22, 1971, for constrictable Tube Valve" and assigned to the sameassignee as the present application, there is disclosed and claimed aconstrictable tube valve of novel construction. As described in saidcopending application, clamps disposed at opposite sides of a tube ofpolytetrafluoroethylene (PTFE) resin or other crack sensitive materialmaintain regions at each side of the tube in constantly constrictedfluid sealing condition free from crack inducing flexure secured insealing embrace about a smoothly curving filler piece. A pair ofcompressor members cooperate with the edge clamped tube to provide aconstrictable tube valve wherein the crack sensitive material of thetube will not be induced to crack upon valve manipulation. The valvedisclosed in said copending application employs a simple tube generallyof uniform wall thickness relying upon the edge clamps and the tillerpiece for maintaining the side edges of the tube in constantlyconstricted condition without inducing through-the-wall cracks therein.The present invention is directed to an alternative arrangement forpreventing through-the-wall cracks from being developed in a cracksensitive tube which is subjected to repeated constriction.

While the aforesaid copending application describes an arrangement whichavoids the formation of cracks by not subjecting the tube material tocrack inducing stress, the present invention provides a tube of specialconfiguration whereby the propagation of a crack-is directedorcontrolled such that, although cracking is not totally precluded,through-the-wall cracking does not occur. g

In accordance with one aspect of the present invention there isprovided, in a valve of the type in which a constrictable tube ismechanically flattened to form a barrier to the flow of fluid materialtherethrough, the improvement comprising: a constrictable tube having aflexible wall and an internal circumferential rib; means disposed atopposite sides of the tube for maintaining a region at each sidecoinciding with the rib in constantly constricted fluid sealingcondition; and mechanical compressor means for adjustably constrictingthe remainder of the tube coinciding with the rib between the regionsfor controlling the closing of the valve.

The invention will be better understood after reading the followingdetailed description of a presently preferred embodiment thereof withreference to the appended drawings in which:

FIG. 1 is a transverse sectional'view showing the basic elements of aconstrictable tube valve employing a constrictable tube formed inaccordance with the present invention;

FIG. 2 is a fragmentary sectional view taken along the line 2-2 in FIG.1;

FIG. 3 is a plan view of the constrictable tube employed in the valve ofFIG. 1 with the edge clamps installed but prior to installation in thevalve assembly;

FIG. 4 is a transverse sectional view taken along the line 4-4 in FIG.3;

FIG. 5 is a fragmentary sectional view taken along the line 5-5 in FIG.4; and

FIG. 6 is an enlarged fragmentary view showing the nature of crackdevelopment and control in the tube wall as constructed in accordancewith the invention.

The same reference numerals are employed throughout the various figuresof the drawings to designate the same or similar parts.

Referring now to the drawings, the basic components of the valve areshown in FIG. 1. The valve construction may take the same form, exceptfor the tube configuration, as the valve disclosed in the aforesaidcopending application to which reference may be had for a more detaileddescription. As seen in FIG. 1 hereof, the valve consists of a housing10 which is formed in two halves divided longitudinally and boltedtogether in a manner not shown. A valve handle 11 enables manipulationof a valve stem 12 having oppositely threaded zones 13 and 14. An uppercompressor member 15 is threadedly engaged with the threaded zone 14 ofthe valve stem 12 while a lower compressor member 16 formed integralwith a yoke 17 is threadedly engaged with the threaded zone 13 of valvestem 12. Restraining pins 18 and 19 engage the yoke 17 for preventingrotation thereof within the housing 10. Guide pins 20 and 21 restrainthe upper compressor member 15 from rotating relative to the yoke 17.The arrangement is such that when the valve handle 11 is manipulated inthe valve opening direction, usually counterclockwise, the compressormembers 15 and 16 move in opposite directions away from each other topermit the tube element 22, confined therebetween, to expand and permitfluid therethrough. Reverse manipulation of the valve handle 11 causesthe compressor members 15 and 16 to approach each other and therebyclose the valve.

As best seen in FIGS. 2, 4 and 5 of the drawings, the constrictable tube22 employed in the valve of the present invention is provided with aninternal circumferential rib 23 intermediate the ends of the tube andpreferably near its center. The ends of the tube are suitably flared asshown in FIG. 3.

In a manner somewhat similar to that described in the aforesaidcopending application, the opposite side edges of the tube 22 aremaintained in constantly constricted condition by the edge clamps 24 and25 located coincident with or overlying the internal rib 23. Each edgeclamp 24 and 25 is composed of two identical clamp halves '26. Twoscrews 27 and 28 inserted from opposite sides secure the halves 26, 26together, as shown. The individual clamp halves may be constructedsubstantially the same as those illustrated in greater detail in theaforesaid copending application. However, it will be understood that theinternal configuration of the surface embracing the tube wall may beslightly different in order to accommodate the tube with internal ribrather than the simple tube with a filler piece.

As best seen in FIG. 6, when the tube 22 constructed in accordance withthe present invention is constricted at its edge a crease line occurs atthe point 29 at the radially inner surface of rib 23 runninglongitudinally of the tube. As will be readily apparent, maximumstresses are localized at the crease line at point 29 and cracks such asthose represented at 30 and 31 may develop. Due to the provision of theinternal rib 23 such cracks originate at the inner wall of such rib.Propagation naturally tends to occur in a longitudinal directionrelative to the axis of the tube rather than in a radial direction.However, longitudinal propagation of a crack such as those shown at 30and 31 is interrupted when the side walls 32 and 33 of the rib (bestseen in FIG. are encountered. The main wall of the tube is under lessstress and free from crack inducing folds. Thus, through-thewall cracksdo not materialize.

it should also be apparent from a consideration of FIGS. 1 and 4 thatthe normal flexing of the tube during opening and closing of the valvewill not produce in the tube wall any further crack inducing bends. Itwill also be seen from FIG. 2 that the compressor members overlie orcoincide with the rib and bring the rib surfaces together to close thevalve.

The present invention is particularly well suited to the production ofvalves employing a constrictable tube formed from PTF E or similarinelastic crack sensitive resin. A tube from such material may be formedwith an internal rib either by machining from a thick wall tubestructure or by isostatic molding or similar molding technique. Itshould also be apparent to those skilled in the art that the actualcross sectional configuration of the rib as seen in H68. 2 and 5 may bevaried while still relying upon the principles implicit in'the presentdisclosure.

Having described a presently preferred embodiment of the invention itshould be understood that various changes may be made therein withoutdeparting from the true spirit of the invention as defined in theappended claims.

What is claimed is:

1. In a valve of the type in which a constrictable tube is mechanicallyflattened to form a barrier to the flow of fluid material therethrough,the improvement comprising: a constrictable tube having a flexible walland an internal rib extending around the entire circumference thereof;means disposed at opposite side edges of said tube for maintaining aregion at each side edge coinciding with said rib in constantlyconstricted fluid sealing condition; and mechanical compressor means foradjustably constricting the remainder of the tube coinciding with saidrib between said regions for controlling the closing of said valve.

2. A valve according to claim 1, wherein said means disposed at oppositeside edges of said tube comprises at each side edge a clamping devicedisposed on the exterior of said tube, said clamping device beingconstructed and arranged to constrict the side edge of said tubesufficiently to crease the radially inner surface of said rib developinga fluid seal thereat.

3. A valve according to claim 2, wherein said tube consists essentiallyof a fluorocarbon resin.

4. A valve according to claim 3, wherein said resin ispolytetrafluoroethylene.

5. A constrictable tube for use in a valve wherein the tube ismechanically flattened to form a barrier to the flow of fluid materialtherethrough, said tube having a flexible wall and an internal ribextending around the entire circumference thereof located intermediateits ends, the material of said tube being substantially inelastic andcrack sensitive but such that when regions at each side edge of saidtube coinciding with said rib are folded and restrained in fluid sealingcondition, the remainder of the tube coinciding with said rib betweensaid regions is capable of being constricted for closing said valvewithout causing the development of a through-the-wall crack.

6. A constrictable tube according to claim 5, wherein said materialconsists essentially of a fluorocarbon resin.

7. A constrictable tube according to claim 6, wherein said materialconsists essentially of polytetrafluoroethylene.

1. In a valve of the type in which a constrictable tube is mechanicallyflattened to form a barrier to the flow of fluid material therethrough,the improvement comprising: a constrictable tube having a flexible walland an internal rib extending around the entire circumference thereof;means disposed at opposite side edges of said tube for maintaining aregion at each side edge coinciding with said rib in constantlyconstricted fluid sealing condition; and mechanical compressor means foradjustably constricting the remainder of the tube coinciding with saidrib between said regions for controlling the closing of said valve.
 2. Avalve according to claim 1, wherein said means disposed at opposite sideedges of said tube comprises at each side edge a clamping devicedisposed on the exterior of said tube, said clamping device beingconstructed and arranged to constrict the side edge of said tubesufficiently to crease the radially inner surface of said rib developinga fluid seal thereat.
 3. A valve according to claim 2, wherein said tubeconsists essentially of a fluorocarbon resin.
 4. A valve according toclaim 3, wherein said resin is polytetrafluoroethylene.
 5. Aconstrictable tube for use in a valve wherein the tube is mechanicallyflattened to form a barrier to the flow of fluid material therethrough,said tube having a flexible wall and an internal rib extending aroundthe entire circumference thereof located intermediate its ends, thematerial of said tube being substantially inelastic and crack sensitivebut such that when regions at each side edge of said tube coincidingwith said rib are folded and restrained in fluid sealing condition, theremainder of the tube coinciding with said rib between said regions iscapable of being constricted for closing said valve without causing thedevelopment of a through-the-wall crack.
 6. A constrictable tubeaccording to claim 5, wherein said material consists essentially of afluorocarbon resin.
 7. A constrictable tube according to claim 6,wherein said material consists essentially of polytetrafluoroethylene.